Genetic testing has become a critical component in the diagnosis and management of IRDs1
For patients living with an IRD, a complete diagnosis requires a clinical and genetic diagnosis2*
*Genetic testing should be accompanied by patient consent and full genetic counselling.
>50% of patients with IRDs have early childhood onset4,5 which progresses rapidly to legal blindness by their early teenage years.4,6
>270 genes associated with IRDs7:
Genetic testing is essential to identify or exclude the subtypes of IRDs.8
- To identify patients early for treatment or clinical trials.8
- To prevent delay in referral and access.8
- Can lead to improved prognosis if there is treatment available (gene therapy).
Genetic tests can improve the accuracy of diagnoses and prognoses, can improve the accuracy of genetic counselling, can reduce the risk of disease occurrence or recurrence in families at risk, and can facilitate the development and delivery of mechanism-specific care3 for retinal disorders, genetic testing should be carried out upon presentation by an ophthalmologist with expertise in IRDs2
American Society of Ophthalmology – Recommendations for genetic testing should be carried out upon presentation by an ophthalmologist with expertise in IRDs.
2019/2020 NHS National Genomic Test Directory for Rare and Inherited Disorders states.16
Patients want to know more: 90% of IRD patients want a genetic test.17
“If it assists in diagnosis, if it assists in pinpointing where problems lie, it can only be a good thing.”18
Patients report that naming their disease and the opportunity to learn more about the genetic cause is invaluable.17–19
A genetic test is essential to making critical life decisions.17,18
- Disease management, family planning, potential therapeutic options and clinical trials.2,17–19
The potential of a future treatment gives patients hope.17,18
The only way to confirm eligibility for gene therapy is by a genetic test.2,3
- Ensure that genetic counselling is offered to patients and gain informed consent to carry out the genetic testing.
- Make sure to explain to the patient the nature of the genetic test.
- Explain to the patient that this will be examining specifically the retinal genes and not the wider genome.
- Ensure that you explain the inheritance patterns relating to the retinal genes.
How to order a test:
- Complete the request form.
- Remember to provide as much clinical detail as possible.
- Clinical scientists have access to a full clinical phenotypic picture when matching a variant.
To complete the test, take 5–10 ml venous blood in an EDTA tube and send to the laboratory along with the completed request form.
There are 3 genomic laboratory hubs (GLH) across the UK:
- London North GLH led by Great Ormond Street Hospital for Children NHS Foundation Trust
- North West GLH led by Manchester University NHS Foundation Trust
- West Midlands, Oxford and Wessex GLH
The usual NHS turnaround target to provide results of the genetic testing is 84 days.20,21
This form is publicly available from the GOSH laboratory website22. To download a referral form and to find out the current turnaround times, please visit the relevant laboratory website.
GOSH, Great Ormond Street Hospital.
Understanding a genetic report
An example genetic report has been provided and outlines:
- Details of the referrer and details of the patient.
- A list of the reasons for referral, including all relevant clinical information.
- The genetic mutations that are present. In the example it shows two mutations in the USH2A gene.
- The evidence as to why these mutations are disease-causing, giving references to published papers for more information.
- Further guidance, e.g. recommendations for parental segregation.
Give patients with IRDs the opportunity for a complete diagnosis with a clinical and genetic test.2
IRD, inherited retinal dystrophy.
- Retina Today. Genetic testing as a new standard of care. 2018. Available at: https://retinatoday.com/articles/2018-sept/genetic-testing-as-a-new-standard-of-care (Accessed August 2020).
- American Academy of Ophthalmology® , IRD Clinical Statement. 2016. https://www.aao.org/clinical-statement/recommendations-on-clinical-assessment-of-patients (Accessed April 2020).
- Lee K and Garg S Genet Med 2015;17(4):245.
- Chung D et al. Am J Ophthal 2019;199:58–70.
- Holtan JP et al. Acta ophthalmol 2019. doi:10.1111/aos.14218.
- Galvin O et al. Clin Ophthalmol 2020;14:707–719.
- RetNet. https://sph.uth.edu/retnet/sum-dis.htm#A-genes (Accessed April 2020).
- Royal College of Opthalmology. Genomics Services Guidance. 2020. https://www.rcophth.ac.uk/wp-content/uploads/2020/03/Genomics-Services-Guidance-2020.pdf (Accessed April 2020).
- Khan Z et al. Int J Adv Med 2016;1–8.
- Hamblion E et al. Invest Ophthalmol Vis Sci 2011;52(11):7981–7986.
- Dale N and Sonksen P. Dev Med Child Neurol 2002;44(9):613–622.
- Senthil M et al. JPRO 2017;1(1):15.
- Bittner AK et al. Optometry 2010;81(9):461–468.
- Liebermann L et al. J AAPOS 2017;21(3):183–e1.
- Shire Rare Disease Impact Report. 2013. https://globalgenes.org/wp-content/uploads/2013/04/ShireReport-1.pdf (Accessed April 2020).
- NHS National testing guide. https://www.england.nhs.uk/wp-content/uploads/2018/08/rare-and-inherited-disease-eligibility-criteria-march-19.pdf (Accessed July 2020).
- Willis TA et al. Br J Ophthalmol 2013;97(9):1148–1154.
- Coombs R et al. Eur J Hum Genet 2013;21:1209–1213.
- McVeigh E et al. J Community Genet 2019;10:425–434.
- NHS North West. NHS England Target Report Turnaround Times (Rare Disease). 2018. Available at: https://mft.nhs.uk/app/uploads/2020/09/tunraround-times.pdf (Accessed September 2020).
- Manchester Centre for Genomic Medicine. Reporting of Results. 2018. Available at: https://www.mangen.co.uk/healthcare-professionals/manchester-genetic-diagnostic-laboratory/general-information/reporting-of-results/ (Accessed September 2020).
- NHS North Thames. Genetic Test Request Form. 2020. http://www.labs.gosh.nhs.uk/media/1395960/joint_genetics_request_form_oct_2020.pdf (Accessed October 2020).